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1. Fully desktop fabricated flexible graphene electrocorticography (ECoG) arrays

   https://doi.org/10.1088/1741-2552/acae08  

   Hu, Jia; Hossain, Ridwan Fayaz; Navabi, Zahra S; Tillery, Alana; Laroque, Michael; Donaldson, Preston D; Swisher, Sarah L; Kodandaramaiah, Suhasa B (January 2023, Journal of Neural Engineering)

   Abstract Objective: Flexible Electrocorticography (ECoG) electrode arrays that conform to the cortical surface and record surface field potentials from multiple brain regions provide unique insights into how computations occurring in distributed brain regions mediate behavior. Specialized microfabrication methods are required to produce flexible ECoG devices with high-density electrode arrays. However, these fabrication methods are challenging for scientists without access to cleanroom fabrication equipment. Results: Here we present a fully desktop fabricated flexible graphene ECoG array. First, we synthesized a stable, conductive ink via liquid exfoliation of Graphene in Cyrene. Next, we established a stencil-printing process for patterning the graphene ink via laser-cut stencils on flexible polyimide substrates. Benchtop tests indicate that the graphene electrodes have good conductivity of ∼1.1 × 10 3 S cm −1 , flexibility to maintain their electrical connection under static bending, and electrochemical stability in a 15 d accelerated corrosion test. Chronically implanted graphene ECoG devices remain fully functional for up to 180 d, with average in vivo impedances of 24.72 ± 95.23 kΩ at 1 kHz. The ECoG device can measure spontaneous surface field potentials from mice under awake and anesthetized states and sensory stimulus-evoked responses. Significance: The stencil-printing fabrication process can be used to create Graphene ECoG devices with customized electrode layouts within 24 h using commonly available laboratory equipment. 

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2. Self-aligned, inkjet-printed resistors on flexible substrates with excellent mechanical stability, high yield, and low variance

   https://doi.org/10.1088/2058-8585/ad396f  

   Hartnett, William N; Nguyen, Jonathan; Francis, Lorraine; Frisbie, C Daniel (April 2024, Flexible and Printed Electronics)

   Abstract Resistors are basic yet essential circuit components that must be fabricated with high precision at low cost if they are to be viable for flexible electronic applications. Inkjet printing is one of many additive fabrication techniques utilized to realize this goal. In this work, a process termed self-aligned capillarity-assisted lithography for electronics (SCALE) was used to fabricate inkjet-printed resistors on flexible substrates. Capillary channels and reservoirs imprinted onto flexible substrates enabled precise control of resistor geometry and straightforward alignment of materials. More than 300 devices were fabricated using poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) as the resistive material and silver as the electrode material. By varying PEDOT:PSS ink formulation and resistor geometry, resistances spanning from 170 Ω to 3.8 MΩ were achieved. Over 98% of devices were functional and the relative standard deviation in resistance ranged from 3% to 18% depending on resistor length and ink composition. The resistors showed no significant change in resistance after 10 000 cycles of bend testing at 1.6% surface tensile strain. In summary, this work demonstrated a fully roll-to-roll compatible process for inkjet printing resistors with superior properties. 

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3. Experimental Assessment and Data-Driven Modeling of Three-Dimensional-Printed Conductive Patterns on Electrospun Substrates

   https://doi.org/10.1115/1.4069361  

   Zuniga, Pablo Andres; Zuniga-Navarrete, Christian; Segura, Stalin Jamil; Guo, Zipeng; Baidya, Sabur; Narvaez-Munoz, Christian; Koehne, Jessica; Segura, Luis Javier (December 2025, Journal of Micro and Nano Science and Engineering)

   Abstract Flexible electronics (FE) have emerged as a key technology with applications in various fields, e.g., energy storage and bio-electronics. Electrospinning (ES), inkjet printing (IJP), and intense pulsed light (IPL), constitute a flexible multistage system capable to handle high customization requirements. The ES/IJP/IPL system is used for flexible substrate fabrication, conductive patterns printing, and sintering, respectively. Although the ES/IJP/IPL system seems to be suitable for on-demand FE devices manufacturing, the correlation of materials and process parameters of individual stages (i.e., ES/IJP/IPL) with the FE devices performance (i.e., conductivity) remains unexplored. Therefore, the objective of this paper is to evaluate the integration of ES, IJP, and IPL, for future production of high-performance FE devices. Various materials and process parameters are used to investigate their influence on the FE device resistivity, including different polyacrylonitrile (PAN) concentrations, voltage regimes, flow rates and the collector types in ES, and distinct number of ink layers in IJP. The study includes (1) an experimental assessment of the electrospun membrane morphology (e.g., fiber diameter) and ink coating characteristics (e.g., ink penetration) using scanning electron microscopy (SEM), and (2) a data-driven analysis through logistic regression (LR), Gaussian process (GP), and Bayesian neural network (BNN) classification models to predict FE conductive feasibility. The results indicate that membranes with larger fiber diameters benefit ink penetration, printed layer/multilayer consistency, and conductivity. This is corroborated with the classification models, where the number of printed layers, fiber diameter, and collector type, are identified as significant factors for accurately predicting conductive patterns feasibility. 

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4. A Low-Cost Wearable Flexible Sensor with an Ag-hBN Interface for Respiratory Monitoring

   https://doi.org/10.1109/BATS67559.2025.11336178  

   Adry, Tasnim Zaman; Sharmin, Sabiha; Islam, Syed Kamrul; Haider, Mohammad Rafiqul (October 2025, IEEE)

   Flexible sensors fabricated via inkjet-printing offer a scalable, low-cost approach for wearable health monitoring applications. In this work, a highly responsive breath sensor is demonstrated based on interdigitated silver (Ag) electrodes printed on a polyethylene terephthalate (PET) film substrate using a Voltera V-One PCB printer, strategically functionalized with hexagonal boron nitride (hBN) nanoparticles at the electrode interface. Systematic testing reveals that the addition of h-BN enhances current conduction compared to pure Ag electrodes, attributed to improved interfacial charge transfer properties. The optimized sensor exhibits distinct, reproducible current profiles during inhalation and exhalation cycles, enabling realtime monitoring of respiration patterns. Comprehensive characterization through high-resolution digital microscopy, sensitive LCR measurements, and COMSOL Multiphysics® simulations demonstrates h-BN's critical role in modulating electric field distribution and boosting sensitivity. This mechanically robust, inkjet-printed (iJP) platform, with a low production cost, shows significant promise for wearable respiratory monitoring in both clinical settings and fitness applications, offering advantages in scalability and performance over conventional approaches. 

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5. Enhanced electrochemical biosensor and supercapacitor with 3D porous architectured graphene via salt impregnated inkjet maskless lithography

   https://doi.org/10.1039/C8NH00377G  

   Hondred, John A.; Medintz, Igor L.; Claussen, Jonathan C. (April 2019, Nanoscale Horizons)

   Advances in solution-phase graphene patterning has provided a facile route for rapid, low-cost and scalable manufacturing of electrochemical devices, even on flexible substrates. While graphene possesses advantageous electrochemical properties of high surface area and fast heterogenous charge transport, these properties are attributed to the edge planes and defect sites, not the basal plane. Herein, we demonstrate enhancement of the electroactive nature of patterned solution-phase graphene by increasing the porosity and edge planes through the construction of a multidimensional architecture via salt impregnated inkjet maskless lithography (SIIML) and CO 2 laser annealing. Various sized macroscale pores (<25 to ∼250 μm) are patterned directly in the graphene surface by incorporating porogens ( i.e. , salt crystals) in the graphene ink which act as hard templates for pore formation and are later dissolved in water. Subsequently, microsized pores (∼100 nm to 2 μm in width) with edge plane defects are etched in the graphene lattice structure by laser annealing with a CO 2 laser, simultaneously improving electrical conductivity by nearly three orders of magnitude (sheet resistance decreases from >10 000 to ∼50 Ω sq −1 ). We demonstrate that this multidimensional porous graphene fabrication method can improve electrochemical device performance through design and manufacture of an electrochemical organophosphate biosensor that uses the enzyme acetylcholinesterase for detection. This pesticide biosensor exhibits enhanced sensitivity to acetylthiocholine compared to graphene without macropores (28.3 μA nM −1 to 13.3 μA nM −1 ) and when inhibited by organophosphate pesticides (paraoxon) has a wide linear range (10 nM to 500 nM), low limit of detection (0.6 nM), and high sensitivity (12.4 nA nM −1 ). Moreover, this fabrication method is capable of patterning complex geometries [ i.e. interdigitated electrodes (IDEs)] even on flexible surfaces as demonstrated by an IDE supercapacitor made of SIIML graphene on a heat sensitive polymer substrate. The supercapacitor demonstrates a high energy density of 0.25 mW h cm −3 at a power density of 0.3 W cm −3 . These electrochemical devices demonstrate the benefit of using SIIML and CO 2 laser annealing for patterning graphene electrodes with a multidimensional porous surface even on flexible substrates and is therefore a platform technology which could be applied to a variety of different biosensors and other electrochemical devices. 

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